Four compounds either being tested or being considered for testing by the NTP were investigated. Two major urinary metabolites of 1,2-dihydro-2,2,4-trimethylquinoline were identified as the 0-sulfate conjugte of 1,2-dihydro-6-hydroxy-2,2,4-trimethylquinoline. The chemical disposition and to some extent the covalent binding of l-chloro-2-methylpropene and 3-chloro-2-methylpropene were investigated. The most noteworthy observation in these studies is that about 33% of the dose of 1-chloro-2-methyl propene is exhaled, unmetabolized, in the first 6 hr. The major urinary metabolite of 3-chloro-2-methylpropene was found to be N-agetyl-S-(2-methylprop-2-enyl)-L-cysteine. It was demonstrated that the naturally-occurring flavone, kaempferol, was hydroxylated to give quercetin in vivo.